With recent advances in digital technology, a radiographic image is transformed into a digital image signal, which is displayed on a CRT or the like or printed out upon being subjected to image processing such as frequency processing. This frequency processing generally includes so-called sharpening processing which adds high-frequency components to an original image. Image processing which makes noise inconspicuous is also performed by smoothing an original image. As described in Japanese Patent Laid-Open No. 2002-92588, medical image processing recently starts using multi-frequency processing which performs frequency processing by separating an original image into a plurality of high-frequency coefficients for respective frequency bands and increasing or decreasing the high-frequency coefficient for each frequency band.